The present invention relates to processed coconut outer husk chops which drain well, have a low tannin content and a high iron content and are used as a planting material, an inert medium for hydroponics and a bed for propagating the decontaminating microorganism suited to propagation of a decontaminating microorganism eliminating a malodorous substance and a trace pollutant from air.
Conventionally, sphagnum, pumice, hydroculture and peat moss have been used as a planting material in cultures of flowering plants such as an orchid, a chrysanthemum, a carnation, a cyclamen and a Turkey broad bellflower, of foliage plants, of high grade vegetables such as a celery, a melon and a strawberry, and of fruit trees. These materials rot easily or serve as an ineffective media for growing plants. In particular, they cause plants to poorly spread their roots.
Recently, in culturing vegetables such as a celery, a melon, a lettuce, a tomato and a strawberry, hydroponics has become popular. The seeds are implanted in an inert medium containing no nutrient, and properly prepared nutrients are fed to the vegetables to forcibly culture them without pollution by various germs to secure high quality and yield of the vegetables.
Requirements of an inert medium for hydroponics include a hardness sufficient to hold a plant to be cultured, pores to hold air and a nutrient solution, the ability to drain well and cause the roots of the plant to spread well, and being clean. Now, rock wool is widely used as the inert medium for hydroponics in view of the root spread and the porosity.
While it is not preferable that a planting material has a high tannin content because tannin shrinks the plant root to suppress growth of the plant, the ligneous part of the plant has a high tannin content, and coconut outer husk also has a high tannin content. Thus, when coconut outer husk is used as the culture medium, a plant cannot sufficiently grow on account of the influence of tannin. Even if coconut outer husk is repeatedly subjected to a water soaking in order to previously remove tannin, tannin seeps little by little for a long time. Thus, a sufficient amount of tannin cannot be removed from coconut outer husk.
The present inventor provided in Japanese examined patent application publication SHO. 63-52848 a planting material suited to a culture medium in a flowerpot and in a soil amelioration. This planting material comprises coconut outer husk chops which were compressed at substantially right angle to the direction of coirs and subsequently chopped. The compression facilitated the seeping of tannin into water during water soaking of the coconut outer husk, so that a cycle of the water soaking and the dehydration of the coconut outer husk is repeated twice or three times to sufficiently reduce the tannin content so as not to adversely affect growth of a plant. Since the coconut outerhusk chops have the elasticity of a sponge to take in air, they provide a desirable planting material.
However, when the prior art processed coconut outer husk chops are used as the planting material in the flowerpot, they must be repeatedly subjected to the cycle of the water soaking for about 10 hours, the dehydration for the seepage of tannin before use. Since the coconut outer husk is previously compressed, tannin very easily seeps into water from it. Thus, the repeated cycle can remove tannin from coconut outer husk until tannin dies bit cause a problem for the growth of the plant.
In hydroponics, the inert medium after harvesting of the plant has root fragments adhering thereto and the root fragments enable pathogenic fungi to grow, so that the inert medium can be repeatedly used only three or four times. While the used inert medium must be discarded, rock wool does not decompose at all nor can it be incinerated at all. Thus, discarding a large volume of rock wool after harvesting of a plant causes environmental pollution.
Since the inert medium for hydroponics is not expected to feed a plant with a nutrient, the composition of a nutrient solution to be fed must be continuously changed in response to the growth stage of the plant. The inert medium preferably has a buffering action of absorbing and storing the nutrient when the amount of the nutrient is excessive and gradually releasing the nutrient when the amount of the nutrient is deficient. While rice hulls have such buffering action, they do not have a sufficient buffering action.
In addition, hydroponics tends to provide poor drainage and cause root rot. While the drainage power of an inert medium with a large number of coirs is enhanced, the fertilizer holding power of the inert medium is reduced.
Therefore, hydroponics cannot ideally grow a plant. The ligneous part of a plant has the fertilizer holding power and on the other hand contains much tannin. As described above, tannin shrinks the plant root to suppress growth of the plant, so that the inert medium with much tannin is not desirable.
In addition, there is a process for removing a malodorous substance from air in which the air with the malodorous substance is forcibly passed through the bottom of a column charged with an absorbent. In this process, the absorbent completely fails when the quantity of the malodorous substance exceeds the capacity of the absorbent, so that the absorbent must be frequently replaced and the pressure drop through the column with the absorbent is high. Thus, this process has many problems in practice.
Recently, a process has been proposed which comprises the steps of charging a column with a peat moss or ceramic material, propagating a particular microorganism nurtured with a particular pollutant on the surface of the peat moss or ceramic material, and passing air with the pollutant through the column to clean the air.
However, a stiff porous microorganism propagating bed cannot be obtained which has a high affinity with the particular microorganism and does not much increase an air passage resistance even if numerous microorganisms propagate. Thus, this process does not have the expected advantage.